1. Field of the Invention
The invention is directed to an electric thin-film circuit in which various thin films form the circuit and the components are formed from these thin films by selective etching.
2. Prior Art
The U.S. patent application Ser. No. 408,100 of Oct. 19, 1973 explains in detail that tantalum-aluminum alloys are well suited for electric thin-film circuits disposed upon a substrate made of an insulator material, and that particularly favorable electric values are obtained in view of temperature coefficients and the time constancy, when the tantalum content is relatively low, compared with the aluminum content, for instance in the range between 2 and 20 atomic percent.
It was stressed in this application that the aluminum forms a so-called face-centered cubic lattice (fcc lattice), in the case of a tantalum content of approximately 7 atomic percent or less, instead of forming a tetragonal lattice as this is the case with a higher tantalum content. This fcc lattice entails a great time stability of the finished electric components which were produced in accordance with this tantalum-aluminum thin-film technique.
The present invention proceeds from this suggestion and provides a thin-film circuit utilizing tantalum-aluminum layers of different tantalum contents and comprising a capacitor and at least one conductor path and/or at least one resistor, whereby the tantalum-aluminum oxide layer forming the capacitor dielectric is produced as independently as possible from the conductor path or the resistor path, in order to minimize production tolerances.